I'm currently teacher training (CELTA intensive, just completed week 1) and need to prepare a lesson for my group next week. It's a group of 12 upper-intermediate students, all around 20yrs old (ish), mostly Spanish.

I have to teach a (40 minute) lesson on 'should have/could have/would have' and have been given very little instruction. I've been round and about and inside out this every which way (I can see) possible in my head and planning, but am still not clear as to the best way to approach this (surely the 3rd conditional is a lesson in itself?). It's the 'would have' which seems to be causing me the most problems in terms of linking it in with 'should have' (advice/regret) and 'could have' (possibility).

As it's only a 40 minute lesson, I'm wondering too whether I'll have time to deal with the negative and question forms, as well as focus on good pronunciation (bearing in mind contractions) of the three model sentences.

Where I'm up to so far is thinking I should try to elicit my model sentences by starting with the present tenses (should/could/would) and converting to the past tenses. But I'm not confident that I'm on the right track (and am also concerned that my eliciting won't succeed and/or my learners will be confused by the differences between the three).

Obviously I'll be going to my tutors with this on Monday, but in the meantime, if you have any tips I'd be very glad to hear them.